📊 Full nutrition facts — per 100g
| Nutrient | Amount | % Daily value | Level |
|---|---|---|---|
| Calories | 31 kcal | 2% | |
| Carbohydrates | 6.7g | 2% | |
| Dietary fibre | 2.8g | 10% | |
| Sugars | 3.9g | — | |
| GI | ~42 — Low | — | |
| Vitamin C | 34.4mg | 38% | |
| Vitamin B5 | 0.39mg | 8% | |
| Folate | 12µg | 3% | |
| Potassium | 133mg | 3% | |
| Copper | 0.14mg | 7% | |
| Caramboxin | present — neurotoxin | — | |
| Oxalic acid | high | — |
Based on Australian NRV. Source: FSANZ Australian Food Composition Database.
📈 Glycaemic index (GI)
💊 Key vitamins & minerals
✅ Health benefits
Star fruit provides 34.4mg of vitamin C per 100g — 38% of the daily requirement at just 31 kcal. This makes it one of the most vitamin C-efficient foods available, surpassed only by guava, capsicum and kiwi among commonly eaten fruits. For people managing weight while maximising micronutrient intake, star fruit's extreme caloric efficiency (more vitamin C per calorie than almost any other fruit) makes it particularly valuable.
Star fruit contains epicatechin (the primary polyphenol in dark chocolate and green tea), quercetin (the anti-inflammatory flavonol) and gallic acid (the antioxidant found in pomegranate and green tea). These polyphenols contribute to cardiovascular protection via LDL oxidation reduction and anti-inflammatory effects. The combination of high vitamin C with these polyphenols creates synergistic antioxidant activity that supports the fruit's traditional use in Asian medicine for fever reduction, liver tonics and inflammation.
Star fruit is one of the lowest calorie fruits available, providing only 31 kcal per 100g — comparable to cucumber (15 kcal) and celery (16 kcal) in caloric lightness. Its sweet flavour and attractive appearance despite such low caloric density make it excellent for weight management — a satisfying visual and flavour experience with negligible caloric cost. The 2.8g of fibre per 100g and high water content contribute to satiety.
Star fruit has been used in traditional Chinese, Ayurvedic and Southeast Asian medicine for thousands of years as a treatment for fever, urinary tract infections, liver disease, hangover and inflammation. Modern research has found some biological support for these uses: the organic acids have mild diuretic properties, the epicatechin content has hepatoprotective (liver-protective) activity in animal models, and the vitamin C and polyphenols support immune function relevant to fever management.
⚠️ Who should limit or avoid
Star fruit contains caramboxin — a neurotoxin that healthy kidneys excrete efficiently, causing no harm. However, in people with chronic kidney disease (CKD), reduced kidney function, or people on kidney dialysis, caramboxin accumulates to toxic levels and can cause serious neurological effects including persistent hiccups, numbness, vomiting, confusion, seizures, coma and death. Even small amounts of star fruit (a single fruit or a small glass of juice) have caused fatalities in people on dialysis. This warning is absolute — people with any degree of kidney disease must NEVER consume star fruit or star fruit juice. This is one of the most clinically serious food-drug/food-disease interactions known.
Star fruit inhibits CYP3A4, a liver enzyme responsible for metabolising many common medications including some statins, certain calcium channel blockers (amlodipine), some anticoagulants and immunosuppressants. This interaction is similar to but less well-studied than the grapefruit-drug interaction. People taking medications metabolised by CYP3A4 should check with their pharmacist before regularly consuming star fruit. Those with established drug-grapefruit interactions should consider star fruit similarly suspect.
Star fruit is high in oxalic acid, which can contribute to calcium oxalate kidney stone formation. People with a history of calcium oxalate kidney stones should avoid or strictly limit star fruit. For people without kidney stone history, adequate hydration when eating star fruit minimises this risk.
🛒 How to select & buy star fruit
Ripe star fruit is golden yellow throughout, with the edges of the 5 wings (ridges) turning slightly brown — this is normal and indicates good ripeness, not spoilage. Fully green star fruit is unripe and very tart. Star fruit with significant brown areas beyond the edge ridges or soft wet patches is overripe. The fruit should feel firm throughout with a slight waxy sheen. A ripe star fruit has a pleasant tropical sweet-tart fragrance.
Rinse the fruit. Trim both ends. Slice crosswise into 5–8mm thick slices — each slice reveals the distinctive 5-pointed star shape. Trim the brown edge strips from each slice if desired (this removes the toughest, most tart part). The slices are ready to eat immediately. For garnish use, select the most uniform fruit and cut thicker slices (8–10mm) to better preserve the star shape. Star fruit makes one of the most visually striking fruit garnishes available.
Sweet star fruit (larger, more yellow, 5+ ridges): eaten fresh, in fruit salads, as garnish, in smoothies. Pleasant sweet-tart flavour like a mix of apple, pear and citrus. Sour star fruit (smaller, more angular, green-tinged): used in cooking, chutneys, pickles, sauces and as a souring agent in South and Southeast Asian cooking — similar role to tamarind or lime. Australian supermarkets typically stock the sweet variety. Asian grocery stores may stock both.
🧊 Storage tips & shelf life
Star fruit ripens well at room temperature. Slightly firm fruit will ripen to golden yellow in 3–5 days. Once fully golden yellow, use within 1–2 days at room temperature or refrigerate. Star fruit does not have a strong aroma until very ripe — a pleasant sweet smell indicates readiness.
Ripe star fruit keeps 1–2 weeks refrigerated — it is more durable than many tropical fruits. Store whole in a loose bag in the crisper. Cut star fruit: the exposed flesh browns within hours at room temperature but refrigerates 3 days in a sealed container. Squeeze a little lemon juice on cut surfaces to slow browning.
Star fruit slices freeze reasonably well — freeze in a single layer on a tray first, then bag. Frozen star fruit slices soften significantly on thawing and lose their visual appeal for garnish, but work well in smoothies and juices. The vitamin C content is largely preserved in freezing. Best used within 3 months for flavour quality.
📖 About star fruit — complete guide
Star fruit (Averrhoa carambola) is native to tropical Southeast Asia — most likely originating in Sri Lanka or the Moluccas (present-day Indonesia) with subsequent cultivation throughout South and Southeast Asia over approximately 2,000 years. The genus Averrhoa is unusual botanically because it belongs to the wood-sorrel family (Oxalidaceae) rather than the rose family that includes most orchard fruits. The genus was named in honour of the 12th-century Arab physician Ibn Rushd (known in Latin as Averroes) — a tribute from Portuguese botanist Gomes during the 16th century spread of the plant through Portuguese trading routes. Star fruit is grown throughout tropical Asia, the Caribbean, Central America, Australia and parts of Africa, and the cross-section star shape makes it one of the most visually iconic tropical fruits globally.
The discovery of caramboxin — the neurotoxic amino acid in star fruit — is a relatively recent medical story that transformed star fruit from a curiosity to a clinically significant fruit requiring specific dietary guidance. The first reported cases of star fruit neurotoxicity in kidney disease patients were described in 1980 in Taiwan, with patients developing hiccups, vomiting and neurological symptoms after eating star fruit. The toxic compound was identified as caramboxin (a beta-carboline amino acid derivative) in 2013 by Brazilian researchers. The mechanism: healthy kidneys rapidly clear caramboxin from the bloodstream before it reaches the brain. In patients with impaired kidney function, caramboxin accumulates, crossing the blood-brain barrier and causing glutamate receptor overstimulation (excitotoxicity). Multiple fatalities in dialysis patients from star fruit consumption have been reported globally, including in Australia, leading to nephrology dietary guidelines that absolutely prohibit star fruit for kidney disease patients. For the broad healthy population, caramboxin poses no risk.